<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Document</title>
        <style>
            * {
                padding: 0;
                margin: 0;
            }

            .a, .b {
                width: 200px;
                height: 200px;
                background: red;
            }

            .b {
                background: yellow;
                width: 300px;
                float: right;
            }

            .a {
                float: right;
            }

            .c {
                width: 200px;
                height: 200px;
                background: orange;
                clear: both;
            }



        </style>
    </head>
    <body>

        <div class="a"></div>
        <!-- <div class="b"></div> -->

        <div class="c"></div>
        
    </body>
</html>